Over the weekend I was able to get TTS and Chromecast up and running. I can hook the Chromecast to a portable speaker and get the TTS to work. I can’t seem to wrap my head around hooking the Chromecast up to my AVR and have the TTS over the speakers without having to change inputs. I purchased a small mixer that connects to a mini amp and I tried adding the amp output to the speakers from the AVR, it works but only sorta. Bad sound or bad feedback. Besides Bluetooth speakers around the house how can I get the TTS through the AVR?
I take it you’re connecting the ChromeCast Audio to one of your AVR inputs?
If so, you will indeed need your AVR to be on the right input for the sound to come out.
Is your AVR a smart one that can be driven by HA? If so you can simply change the input just before playing the TTS. If not, I’m not sure how to advise, I don’t know enough about mixers to give you relevant and helpful info I’m afraid